Find the measure of the smaller angle formed by the hands of a clock at the following times. 3:15
Table of contents
- 0. Review of College Algebra4h 45m
- 1. Measuring Angles40m
- 2. Trigonometric Functions on Right Triangles2h 5m
- 3. Unit Circle1h 19m
- 4. Graphing Trigonometric Functions1h 19m
- 5. Inverse Trigonometric Functions and Basic Trigonometric Equations1h 41m
- 6. Trigonometric Identities and More Equations2h 34m
- 7. Non-Right Triangles1h 38m
- 8. Vectors2h 25m
- 9. Polar Equations2h 5m
- 10. Parametric Equations1h 6m
- 11. Graphing Complex Numbers1h 7m
1. Measuring Angles
Angles in Standard Position
Problem 43
Textbook Question
Perform each calculation. See Example 3. 47° 29' ― 71° 18'
Verified step by step guidance1
First, understand that the problem involves subtracting two angles given in degrees and minutes: \(47^\circ 29'\) and \(71^\circ 18'\). Since the second angle is larger, the result will be negative, but we will proceed with the subtraction process as usual.
Convert the minutes part of the angles to a common base and subtract the minutes: subtract \$18'\( from \)29'$. If the top minutes are smaller than the bottom minutes, borrow 1 degree (which equals 60 minutes) from the degrees part before subtracting.
Subtract the degrees: after adjusting for any borrowing, subtract \(71^\circ\) from \(47^\circ\). Remember to account for the borrowing done in the previous step.
Combine the results of the degrees and minutes subtraction to express the answer in degrees and minutes format.
Since the second angle is larger, the final answer will be negative. Express the result with a negative sign to indicate this.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Degrees, Minutes, and Seconds in Angle Measurement
Angles can be expressed in degrees (°), minutes ('), and seconds ("), where 1 degree equals 60 minutes and 1 minute equals 60 seconds. Understanding this notation is essential for performing arithmetic operations on angles accurately.
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Reference Angles on the Unit Circle
Subtraction of Angles in DMS Format
When subtracting angles given in degrees, minutes, and seconds (DMS), you must subtract each component separately, borrowing from higher units if necessary (e.g., borrowing 1 degree as 60 minutes) to avoid negative values in minutes or seconds.
Recommended video:
Adding and Subtracting Complex Numbers
Conversion Between Units for Simplification
To simplify calculations, angles in DMS can be converted to decimal degrees or all to seconds before performing arithmetic, then converted back to DMS. This method helps avoid errors and makes subtraction straightforward.
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Introduction to the Unit Circle
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